[partial solution] try sending audio ONLY from daw's return tracks, not straight from your daw's audio or instrument tracks. So if you want to apply a heavy processing (via a slave VE) to a synth, send it's audio to a return track, place a VE Audio Send on that track, send it to the slave, process, then send back to a VE Instrument.
I find myself in a sad situation: I am sending between a macbook pro and a PC (clean windows 10 install, vep running as admin) via static IP addresses and no router or switch - straight cable between the computers. The transfer speed when copying files (both ways) is 900 Mbps flat, ping 0.3ms, both computers have i7's and SSDs, and the crackles appear even when the server is empty (no plug-ins, just the input, outputs and folders).
Tried all buffer combinations (0-4), threads (1-8), DAW's buffer size (128-2048), (firewalls on/off), no difference whatsoever except for larger CPU usage on the client side for small buffer settings. Tried bouncing to audio, the crackles are there. Every time in the same place-ish - looping a 4-bar loop, the crackles appear at the end of bar 1. Tried Logic and Ableton Live, same thing.
I just realised that I purchased this software 2 years ago for the sole purpose to unload the summing processing to a different computer and never managed to use it for this purpose. I am using it sometimes to better distribute the load over multiple cores when using very hungry synth presets which otherwise would choke a single CPU core.
So... did anyone managed sucessfully with VE Pro to send 16 stereo channels to a slave and receive back 8 stereo channels with no pops and clicks?